Pump with differential impeller control



March 23, 1948. e. HOLT 2,438,442

PUMP WITH DIFFERENTIAL 'IMPELLER CONTROL Filed D80. 21, 1944 14 r 123 H1 24$ 24 C i if Patented Mar. 23, 1948' PUMP WITH DIFFERENTIAL IMPELLER CONTROL Ray G. Holt, Euclid, Ohio, assignor,

assignments, to Borg-Warner Corporation, cago, 111., a corporation of Illinois by mesne Chi- Application December 21, 1944, semi n6. 569,128 7 Claims. (01. ma-a'n This invention relates to centrifugal impeller pumps and particularly to an improved arrangement for adjusting the position of-the impeller.

Centrifugal impeller pumps are being used to an increasing extent as standby booster pumps located in or adjacent the fuel tanks of aircraft, the driving motor being cut on and off depending upon the demand for pressure. While the centrifugal type of impeller permits of flow therethrough when stationary the same nevertheless ofiers some obstruction to the free passage of fluid thereby.

I have found that this problem can be effectively solved by forming a portion of the fluid channel defining means as part of the housing and forming the remainder of the channel in the rotating impeller together with a-novel arrangement of means for effecting the axial adjustment of the impeller in such a way that when the impeller is not being rotated the same is withdrawn away from the housing portion defining part of the fluid channel whereby to reduce the obstruction to fluid flow through the pump. I have provided means responsive to the development of a pressure differential by the rotation of the impeller effective to move the same axially to bring the pumping channels formed in the impeller into closely spaced relation to that portion of the channel defining means formed as part of the housing, whereby to improve the pumping efficiency of the impeller when the same is being driven.

It is, therefore, the primary object of this invention to provide an improved and novel centrifugal pump arrangement effective to carry out the above mode of operation, which arrangement is both efficient in its operation and practicable of manufacture and installation.

Other objects, advantages, and uses of the present invention will become apparent from a reading of the following specification taken in connection with the accompanying drawing which forms a part thereof and wherein:

Fig. 1 is a broken away cross-sectional view taken on the general axis of a centrifugal pump incorporating a preferred embodiment of the peller showing the arrangement of open-sided spiral pumping grooves formed therein.

Referring in greater detail to the figures of the drawing, there is indicated generally at ill the essential elements of a centrifugal booster pump incorporating a preferred form of the invention. Pump housing ii includes impeller chamber l2 having a coaxial fluid inlet i3 and a surrounding volute discharge chamber l4. Received within pumping chamber I2 is a special impeller and supporting arrangement indicated generally at 2| to which the present invention is particularly directed.

The special impeller: arrangement 2i preferably includes impeller proper 22 mounted in splined or keyed relation on rotatable shaft 23 adapted to be driven by a suitable motor (not shown). Impeller proper 22 includes a radiallyextending disc-like portion 24 formed in the inlet face 26 thereof with a plurality of spirally extending grooves or channels 21 beginning adjacentthe axis and communicating with the outwardly disposed volute chamber l4. The curved invention and showing the impeller in the retracted position occupied thereby when not being rotated;

Fig. 2 is a view similar to that of Fig. l but showing the impeller in the axially adjusted position to which the same is movedin' response to the fluid pressure generated thereby; and

Fig. 3 is a broken away plan view of the imchannel defining walls merge with inlet surface 26 at points 21a and 21b to define the open sides of the channels. Surrounding inlet [3 is a generally transversely extending wall surface Ila complementary to impeller inlet surface 26 and functioning when impeller 22 is in closely spaced relation to this surface Ila to define a substantial closure for the radially outward portion of the channels 21 disposed opposite thereto. This relation is important to the development and maintenance of a pressure differential between inlet i3 and volute chamber M. The spacing between impeller 22 and transverse surface Ila in the pumping position indicated in Fig. 2 is preferably maintained at a very small value of the order of only several ten-thousandths of an inch. This position of the impeller with reference to transverse surface I la shown in Fig. 2 will be referred to for the purpose of description as "the first axial position of the impeller. The outer periphery of impeller 22 is preferably generally parallel to the axis of rotation as indicated at 24a and given a limited small clearance with reference to cylindrical-like portion lib of housing Ii to thus define with the housing and the undersurface 24b of impeller 22 a pressure responsive motive means for effecting the axial adjustment of the impeller into said first position. The limited clearance between cylindrical wall llb of the housing and the cooperating periphery 24a of the impeller func-. tions to admit pressure fluid from volute chamber M to motive chamber 240.

The splined or keyed driving relationship between shaft 23 and impeller 22 preferably includes an axial tubular extension 22a on impeller 22 internally splined at- 28 for cooperation with key 29 received in arcuate recess 3| of shaft 23. Coil compression spring 32 acts between shoulder 33 on shaft 23 and shoulder 22b on impeller extension 22a for urging the impeller from said first position into telescoping position within chamber 240 with the inner terminal of tubular portion 22a in contact with stop 23a on shaft 23, which position will be referred to as the second axial position. In this second position impeller 24 is sufficiently removed axially from transverse surface Ila to eliminate the impeller as an obstructing influence in the path of fluid flow between inlet l3 and volute chamber id at such time as when fluid is being drawn through the pump with impeller 22 remaining stationary.

In addition to the above described structure, I contemplate the provision of the necessary additional elements for complete and satisfactory operation including preferably a screen 34 surrounding the inlet, a converging inlet guide l3a and cooperating beater 36 which may be threadably fastened to' the terminal of shaft 23.

In the normal manner of employing the present arrangement the pump ill will be located in or adjacent the fuel tank remote from and in series with the engine driven pump (not shown). At such time as the pressure condition in the supply line to the engine driven pump is satisfactory booster pump III will be allowed to remain stationary and under such conditions impeller 22 will remain in said second or retracted position shown in Fig. 1 so that impeller will impose no significant or appreciable obstruction to the passage of fluid or fuel from the tank through the pump l and to the engine driven pump. However, should the pressure in the system require the operation of pump ill the same will be placed into operation by suitable conventional means-and immediately upon impeller 22 being rotated a pressure differential will be created between inlet I 3 and volute chamber 14. This pressure in volute chamber I4 is directed between cylindrical wall lib and the periphery 24a of the impeller into motive chamber 240 where the same acts upon pressure responsive piston-like surface 24b forcing the impeller away from said second position shown in Fig. 1 into said first position shown in Fig. 2 wherein the transverse housing wall surface Ila functions to substantially close the radial outer portion of the open side of spiral pumping channels 21 to thus improve the pumping effectiveness of impeller 22. As long as impeller 22 is being driven the pressure differential between inlet l3 and that existing in volute chamber I 4 and motive chamber 240 will be suflicient to maintain impeller 22 in the position shown in Fig. 2 with the im eller in engagement with stop 33 on shaft 23. When this condition no longer exists and shaft 23 has been stopped as by cutting off the energy to the driving motor then coil compression spring 32 becomes effective to shift impeller 22 to said second position with the terminal of tubular extension 2201.- in contact with stop 23a on shaft 23. v

While I have described my invention in connection with a specific embodiment thereof, it will be understood that this is by way of example rather than limitation and that the invention is to be defined by the'appended claims.

'4 I claim: I 1. In a centrifugal impeller pump arrangement including a housing having an impeller chamber therein, a rotatable centrifugal impeller generated by said impeller upon rotation thereofto shift said impeller to the other of said respective positions.

2. In a centrifugal impeller pump arrangement including a housing having a centrifugal impeller chamber therein, a rotatable centrifugal impeller within said chamber, said housing havinga coaxial inlet delivering to said impeller and a surrounding volute chamber for receiving fluid from saidimpeller, said impeller being formed with open spiral pumping channels extending from the central portion of said impeller outwardly and discharging into said volute chamber, said opened sides of said channels facing in the general direction of said inlet opening, said pumping chamber being defined in part by a generally transverse surface surrounding said inlet in complementary opposed relation to a radially outward portion of said channels defining a closure therefor, means defining an axially adjustable support for said impeller and means for adjusting said impeller axially to either a first position in closely spaced relation to said transverse surface or to a second position axially removed therefrom, said first position being effective to improve the pumping efliciency of said impeller and said second position being effective to remove said impeller as an obstruction to flow between said inlet and said volute chamber.

3. In a centrifugal pump including a housing I having a central inlet, a coaxially located rotatable impeller for receiving fluid through said inlet and formed with open spiral pumping channels, a surrounding volute chamber outlet for receiving fluid from said channels, a housing surface surrounding said inlet and extending transversely of the axis of said impeller, the combination therewith of means for supporting said impellr for axial adjustment to either a first position with said impeller in closely spaced relation to said transverse surface or to a second position with said impeller removed axially away from said transverse surface, means for normally urging said impeller in the direction of said second position when said impeller is not said inlet opening extending transversely to the axis of said impeller, at least a portion of which surface is effective to form a substantial closure for the open pumping channels turning adjacent thereto, the combination therewith of axially adjustable supporting means'for said impeller providing for supporting then same in a first axial position in closely spaced relation to said transverse surface and for supporting the same in a second position removed axially away from said first position, means .for resiliently urging said impeller in the direction of said second position and means responsive to the pressure developed by said impeller for moving the same into said first position and maintaining the same in said first position.

5. In a centrifugal impeller pump arrangement including a housing, a rotatable centrifugal impeller in said. housing, a coaxial inlet in said housing for delivering fluid to said impeller, a surrounding volute discharge chamber for receiving fluid from said impeller, said impeller being formed with open spiral pumping channels facing in the general direction of said inlet and extending from the centralportion of said impeller spirally outwardly into communication with said chamber, a surface surrounding said inlet and extending generally transversely to the axis of said impeller in complementary relation to the adjacent portion of said impeller, said surface cooperating with radially outwardly disposed open portions of said channels to form a substantial closure therefor for directing fluid centrifugally outwardly into said volute cham-. ber when said impeller is in a first position, the combination therewith of means for adjustably supporting said impeller in either said first position or a second position removed axially away from said first position with said impeller separated from said transverse surface, said means including a coil compression urging said of disc-like construction received in said chamber, a coaxial inlet for delivering fluid to said impeller and surrounding volute discharge chamber for receiving fiuid from said impeller, a plurality of open-sided spiral pumping channels in the inlet face of said impeller extending from the central portion thereof spirally outwardly, said housing pumping chamber including a surtween said impeller and said supporting shaft normally urging said impeller into said second position, stop defining means carried by said supporting shaft defining the limit of movement of said impeller in said second position, and means defining with the underside of said impeller a pressure responsive motor for moving said impeller in the direction of 'said first named position when the same is rotated to develop a differential of pressure between the inlet and the volute chamber and means for directing the pressure in said volute chamber to said motive means.

7. A centrifugal pump comprising a housing having a central inlet; a volute chamber having an outlet; a rotatable impeller formed with spiral pumping grooves having terminals opening in the direction of said inlet; a transverse wall surface confronting said groove terminals; means for adjustably supporting said impeller with said groove terminals in predetermined spaced relation to said inlet and said transverse surface, said means normally urging said impeller axially away from said surface when said impeller is stationary to reduce obstructing effect of said impeller in the path between said inlet and said volute chamber, said means also including a motive chamber in coactive relationship to said impeller-for effecting axial movement of said impeller in the opposite direction; and means for delivering the pressure fluid generated by the face extending generally transversely to the axis I of rotation of said impeller and in complementary opposed position to the open radially outer portion of said open channels forming a substanrotation of said impeller to said motive chamber whereby to move said impeller into closely spaced relation to said transverse wall surface to improve the pumping efficiency of said impeller.

, RAY G. HOLT.

REFERENCES CITED The following references are of record in the ,flle of this patent:

UNITED STATES PATENTS France 1985 

